Method of desulphurating coal distillation gases



Jilly 9, 1935. BROcHE 2,007,741

METHOD OF DESULPHURATING COALDIS'I'ILLATION GASES Filed Oct. 18, 1932 a f Um ATTORNEY Patented July 9, 1935 r g V V 2,007,741 V METHOD "OF DESULPHURATING COAL DISTILLATION GASES f Hans Broche, Essen/Ruhr,-Germany I r V Application October 18, 1932, Serial No. 638,431

' In GermanyOctober 23, 1931 I 9 Claims; (01. 23-2) g I My invention refers to dry purification of coal The invention obviates this inconvenience and distillation gases from hydric sulphide .(HzS) conincreases remarkably'the quantities of the gas to tained therein'by vmeans of treating the gases be purified per time unit. According to the inm withnatural ma sses, containing iron oxide, as Vention the gas leaving, say the first or secon'd 15 '1im0nite, 0r with artificial masses, as LJX'fHl-QJSS purifier unit is heated so that the further treat- *5 It is well known that such masses can be used as ment of the gasi the Subsequent pur'ifyingiuhit such or after being activated by certain additions or units is carriedthrough at raised temperatures such as calcium carbonate. 'It is further-"known Investigations have proved that .the removalthat such masses if being saturated with sulphur Of emaj quantities. of sulp ted hy n 1-"0 can be freed" therefrom by extraction and can from the incomin fi y the y gas p 10 then be reactivated, I V iying masses occurs extremely rapidly,"render- The purification of the gases. by th ses ing it possible to remove in general far more than referred to has been carried on till, at present l 01' t e Original (ionteht of sulphur the generally in such' way that these masses have t fi t pu fi unit, 50 8 8 eve 7 1'5- been filled into difierentsingle aggregates or units, of this sulp Content and m i Even vif uch l5 7 as for instance containers, cases, tanks, towers first purifying unit is treating gas flowing through or the like, andva plurality of them, mostly from it with considerably higher velocities, the removal 3 to 4, have been assembled to one purifying sysof the major por h f the p r d hydr n tern. l The gas to be purified has been led through IrO' t e c ud 2& Wi Succes y be done.

these'three or four single purifiers in succession T r f re in the following units Ofthe purifying 20' and freedthereby iromhydric sulphide (sul- Sy tem only h fine purificationofth s s phuretted h g to be done but needing a considerably longer time .As a rule, at a suitable stage aii' and/or steam due to the decreased activity of the. mass being has been added to the gas under treatment in converted to a large extent into iron's'ulphideand orderto carry through, besides the'combination the reduced concentrat on Of t p in the 25 of the hydric sulphide with the iron contained-in gas. In this instance the velocities and loads thepurifying mass, a regeneration of the iron mentioned before must not be exceeded, if it is sulphide (Fesz) so formed in a foregoing'unit desired to produce an absolutely pure gas. hereby separating in a second 'or following unit Besides the removal of the sulphur from the gas 36 the elementary sulphur from the converted purithrough dry purification, the regenerationsof the fying mass. It appears therefrom that airand/ or iron sulphide formed in e masses i 0 b Ca ried steam are regularly to be added after the first, or out simultaneously, as mentioned before, in a sec a following u t v 3 I and and followingunit in the path of the gases; 7 i This dry purificationof gas works quite 'reli- Thisregeneration' of the iron sulphide in a ably. A great disadvantage of this process com' second or following purifying .umt likewise occurs 35;

sists, however, in thatthe'regular fiow'fof the-gas considerably slower-than for instance the recepthrough t t nkgbrti as mu tv not exceed a tion of the major quantities of the sulphuretted velocity of from 5rd? rn illimetres per second, if hydrdg' in the first Purifying unit. But only an"entiredesulphuration of the' gas under treat then,- if the iron sulphide being formed is regenib ment'and a-suificie'nt concentration oil-the Smphur erated agaihpermanently, is it possible to operate 40 in the mass is to be ebtained. Therefore it is'not a system of purifiers over an extendedperiod and possible to'load thelpurifiers withlarger volumes to reach sufficient concentrations of sulphur in ofgas and to lead through them larger quantities the'pu'rifying mass. The slow regenerationbf the of gas per time unit're spectively'; Temporarily iron sulphide up to the present was a further such purifiers have "already" been operated on reason for keeping the -velocit1es of-the gas in the about the double velocity of thegas,"as"menunits of a pu'rifying system at'a low figure. If tioned before','that'is to'say, a'greater loading of operating the purifier at higher velocities-ofthe the system has been admitted, but such operation gas, the purifier would become ineffectual very was only possible for" some hours or afewda'ys; duickly',sirice the regeneration of the 1ro'n'sul- 5i? since otherwise sulphuretted hydrogen appeared 1 phid'e could not keep pacewith the quicker bind- '56 '1 rather rapidly in thegas to be purified; I W

At any rate, it has been impossible up to the but would lag behind. a

present to continuously operate the purifyingsys- From this it follows, that there occur with ten'is'with greater loads of gas to be purified than the dry purification of gas rapid reactions, on

' onehand, namelythe removal-of the major pub 555 mg of new sulphuretted hydrogen by the mass indicated-before. 7 7' tions of the initial sulphuretted hydrogen in a first unit, and slow reactions in a second, or following unit, on the other. hand, namely the removal of the last remainders and traces of the sulphur from the gas and the regeneration of the mass. The slow reactions, however, determine the speed of operation of the total plant or system. One is not allowed to actually utilize the high velocity of the gas admissible during the removal of the major portions of sulphur in a first purifier unit in order to fully finish the slow reactions occurring in the purifier unit or units following a first unit.

This invention overcomes this drawback and renders it possible to operate the whole purify ing plant at the same high velocities which are admissible in a first unit of the system of purifiers, in that the slow reactions in the remaining units of the system are accelerated through a rise in the temperature of the gases under treatment whereby the speed of the reactions taking placeinthe following units is equal-' ized about to thatof the rapid reactions in-a first purifying unit.

For instance, the operation can be carried on in such a manner that the gas roughly cleaned in a first purifying unit is heated in suitable heat principally raised by about 10 degrees centigrade,

or more, above the temperature of the gas in a firstpurifying unit. The value of the increase in temperature is governed by and to be chosen in accordance to the property andcondition of the respective gas under treatment, as the contents of sulphur and cyanogen in the gas etc. vary. For instance, itmay prove suitable to work ,in a first purifying unit at the customary daily temperatures of from to degrees centigrade or even somewhat more, and thereupon to maintain the gas by external supply of heat at a temperature of from to degrees centigrade, or more, in a following unit.

In this way it is possible to operate the purifying system at higher speeds of gas than the cus' tomary ones, andto load the plants with quantities of gas up to double the amount, and more, in comparison with those quantities admissible to-day in carrying out the operation with uniform temperature or cold purification,

r In carrying out the invention, a heat exchang ing devicemay be provided for a system of purifiers and the roughly cleaned gas maybe heated after leaving a first purifying unit and then passed to additional purifying units. But it is also possibleto provide a special heat exchanging device, or steamcoils, for each separate tank, tower orthe like and to heat the units thereby separately. In all instances it is possible to carry through the alternate connection of the units, customary at present, which means that in a certain turn the purifying unit in the last place is made to be the first unit, the activity of which has been considerably reduced by the reception of sulphur and its combination with the iron oxide contained in the purifying mass, while now the first purifying unit becomes the second, the second being placed third and so on. 'As mentioned hereinbefore, such regeneration is done by introducing steam and/or air at a suitable stage, i. e. after a first unit of the series. This so-called retrograde connection of the units will assist, in addition, a complete regeneration of the masses in the containers. However, the manner of operation is in no way bound to this kind of con meeting the tanks.

In the drawing a diagrammatic view of a systern is shown' adapted for the performance of the invention. But it is to be understood that the invention is not limited in any way to this ex ample of its performance.

The coal distillation gases, asthey are coming from the furnace and are washed in scrubbers or washers and cooled, enter the dry purification system by the pipe III. This system comprises, in this example, four units II, l2, I3, I4, the units being of the same capacity. Each unit encases the material adapted for dry purification, containing'iron or iron-oxides, or being an artificial purifying material as limonite.

The cool gas enters the first unit in which the purificationis done atnormal or room temperature of about 25 C. In this first unit the principal amounts (about 85-95%) of sulphuretted hydro gen which arepresent in the gas, are removed" from it, and a kind of raw purification of the gases is done hereby, as far as its sulphur content isconcernedh The gases pass now through the pipe I5 in a heater I6, in which their tem-' perature is raised by a minimum of about 10 C. Preferably. the gasesare heated to about 50 or C.: The so heatedigases leave the heater through the pipe I I. and enter the unit I2. There remainders of the sulphurated hydrogen are further removed, but at the same time the revivification of the purifying agentebegins by the action of oxygen of the air or the steam, previously addedto or otherwise contained in the gases, this reaction being considerably accelerated by the heating of the gases. through'the pipe 18 in the unit -I3, and then through the pipe 19 in the unit I4, and leave the purifying system through the pipe 20. The treatment of the gases in the'units I3, HI is done at about the same temperature, as in the unit l2, i. e. at a temperature at least about 10 C. higher than in unit I I, and preferably at about 50 'to' 60 C. 'No additional means are necessary to maintain this temperature after it has once been created in the heater I6, because'the revivification in the subsequent units is accompanied by a development of heat, as being an external process. The heating of the gasin the heater I6 is done ,by heat exchange. The heating medium, for inspecial temperatures or apparatus referred to.

What I claim is:

1. Ina method of removing sulphur from coal distillation gases by'dry purification, passing the gases at a constant speed successively through a plurality of units housing substantially equal The gases pass then amounts of an iron-containing purifying agent the second group at least substantially 10 C.

higher than the temperature in thefirst group, the number of united the second group, and the elevation of temperature in the second group above that of the first group, being such that the speed of the gases depends on the rate of reaction in the first group.

' 2. In a method, as claimed in claim 1', the dimensions of the units for dry'purificationlbeing substantially equal. j I

3; In a method, as claimed in claim 1, passing the gases successively at least through three units, and raising the temperature of the gases by at least 10 C. after the first unit. e

4. In a method, as .claimed in claim 1, raising the temperature of the gases after having passed the first group of purifying units to between about 30 and 60 C.

5. In a method, as claimed in claim 1, adding oxygen containing vapors or gases to, the coal distillation gases, at the latest before entering the second group of purifying units.

6. In a method of removing sulphur from coal distillation gases by dry purification and regenerating the dry purification means by oxygen containing vapors or gases admixed tothe gases, passing the gases successively through a plurality of units housingan iron-containing purifying agent,'said units forming two groups connected-in series, maintaining the temperature in the group through which the gasesfiow first substantially at room temperature and removing the major portion of the impurities in said first group, raising'the temperature of the gases admixed with oxygen containi'ngvapors and gases to between about 30 and 60 C. before'entering the secondgroup in-which substantially all the remaining-impurities are removed, and simultaneous regeneration of the purifying agent is effected, and substantially maintaining said raised temperature of the gases while passing said second group. I

'7; Ina method of removing combinations o sulphur fromcoal distillation gases bydry purification, passing the gases successively through a plurality of units housing an iron-containing purifying'agent, the units being of substantially equal capacity and being connected in series, and

placing the unit through which the gases have flown first to the end of. this series, after said unit has been about saturated with sulphur compounds, operating said units in two groups connected in series, maintaining the temperature in the group through which the gases flow first substantially at room temperature, and maintaining the temperature in the second group between about 30and 60 C., substantially equaliz-' ing hereby the speeds of reaction between the sulphur compounds contained in the gases and the purifying agent in the first group, on one hand, and between the remainders of sulphur compound and the oxygen contained in the gases, and the purifying agent and its combinations with sulphur, on the other hand. a

8. In a method of removing sulphur from coa distillation gases by dry purification, passing the gases substantially at the same speed through a plurality of successive units housing iron-containing purifying ts, vvsaid units formm' "g at least two groups connected in series, the purifying agent in the group through which the gas flowsfirst being of higher activity than thatof the purifying agent in a succeeding group, maintaining the temperature in a group of lower activity at least substantially 10 C.'h'igher than thetemperature in the first group and raising thereby the speed of reaction in the group of lowor activity; 7

9, In a method of removing sulphur from coal distillation gases by dry purification and regenerating the dry purification means by steam admixed to the gases, passing the gases admixed with steam at substantially the same speed through a plurality of successive unitshousing iron-containing purifying agents, said units forming at least two groups connected in series, the group through which'the gasflo-ws first containing the purifying agent of substantially full activity, while a successive group, contains this agent in a state partially used and to be regenerated, maintaining the temperature in the group through which the gas fiows first substantially at .room temperature and in a succeeding group at 

